This invention relates to seals and more particularly to seals for an exhaust nozzle with vectoring capabilities that is movable about multiple axes for a gas turbine engine.
This invention constitutes an improvement over the multi-axis thrust vectoring nozzle described and claimed in U.S. Pat. No. 4,836,451 granted to Herrick et al on Jun. 6, 1989 entitled xe2x80x9cYaw and Pitch Convergent-Divergent Thrust Vectoring Nozzlexe2x80x9d assigned to United Technologies Corporation, the assignee common to this patent application which discloses a yaw and pitch convergent-divergent exhaust nozzle for a gas turbine engine. As disclosed in this patent a pair of cooperating clam shells hinged to a gimbal ring and pivotal about an axis perpendicular to the clam shell hinge axis surrounds the engine""s tail pipe. The clam shells define a variable area nozzle throat which can be selectively directed vertically by rotation of the clam shells about its hinged axis or horizontally by rotation of the clam shells and gimbal ring about the gimbal axis for effectively varying the area of the exhaust nozzle to change or divert the exhaust flow and biasing the exhaust flow for vectoring the aircraft.
As is known in the aircraft engine technology, the prevention of hot mainstream gas or coolant leakage between mating components in multi-function exhaust systems is extremely important. It is of paramount importance that the hot gasses in the exhaust of the engine do not migrate into regions of low allowable temperature substructure and of like importance the compressor air utilized for cooling should not be diverted and prevented from reaching the destination to accomplish the necessary cooling. By preventing the hot gas ingestion, additional low weight, low allowable temperature structures can be utilized with a consequential improvement to the thrust-to-weight ratio. By preventing cooling system leakage, the nozzle performance is enhanced. Therefore, improving sealing technology enhances both aerodynamic and structural efficiency.
As noted in the U.S. Pat. No. 4,836,451 patent supra, arcuate seals disposed between the clamshell spherical surfaces and the collar spherical surface for preventing the flow of exhaust gas therebetween. The type of seals disclosed in this patent are seals, such as piston rings or spring seals.
As one skilled in the seal technology appreciates, seals are generally applied to parts which have relative motion only along a single axis, i.e. rotation or translation. Also, sealing between rotating, pivoting or translating members has been accomplished by techniques that include, for example, labyrinth, finger, piston rings and sheet metal seals. These types of seals have proven to be unsatisfactory for use in an application where the moving components move along multi-axes relative to each other.
We can obviate the problems enumerated in the above by providing a brush seal formed in hemis-spherical portions of a ring that is judiciously located in the convergent flap of a multi-axis vector nozzle. The brush seal comprises an arced or straight brush pieces of a plurality of high compliance high temper wire bristles. It has been found on an experimental rig tests that the seal made in accordance with this invention reduced leakage on the spherical section of the spherical convergent flap nozzle by as much as 44% and 72% when compared to conventional sheet metal and piston ring seals.
An object of this invention is to provide improved sealing means for a multi-axis vector exhaust nozzle for a gas turbine engine of the type that powers aircraft.
A feature of this invention is a brush seal formed in a ring that is judiciously located in the convergent flap of the multi-axis nozzle.
A still further feature of this invention is the utilization of high compliant, high temper, small diameter wire bristles formed in either an arc or straight configuration.
The foregoing and other features of the present invention will become more apparent from the following description and accompanying drawings.